Marshlands in the south east of England could start to disappear in a little over 20 years due to rapid rises in sea levels, scientists have warned.

Studying samples from sediments, sea levels over the past 10,000 years were tracked to study how changes have affected salt marshes.

Ian Shennan at Durham University and colleagues estimate that marshes in the south east of England could start to disappear from the year 2040, and across all of Great Britain by 2100.

The lasting effect of ice removal since the end of the last Ice Age means most of Scotland is rising and southern England is subsiding, which explains the difference in timescales.

The study shows that rising sea levels over the last 10,000 years has led to increased water-logging of the salt marshes, killing vegetation that protects them from erosion and resulting in the marshes retreating landwards.

Salt marshes are coastal wetlands that are flooded and drained by salt water brought in by the tides and can be found along the British coast.

They are a transitional area between water and land and are home to delicate ecosystems.

They also protect coastal areas from erosion by acting as a buffer for waves in storms and reducing flooding by slowing and absorbing rainwater.

Extensive marshes occur along major estuaries around Britain including the Thames, Solent, Bristol Channel, The Wash, Humber, Mersey, Solway Firth, Firth of Forth, Clyde and Cromarty Firth.

“Sea level rise is inevitable over the next 100 years, as it has been over much of the last 10,000 years. The rates differ across Great Britain and we can model these differences,” says Shennan.

“Quantifying the vulnerability of marshes to sea level rise is essential if the threat is to be mitigated over the coming decades.”

The Environment Agency has plans which include allowing new areas to flood, he says.

Journal reference: Nature Communications , DOI: 10.1038/s41467-018-05080-0